Description: Thallus is a thick (to 2 mm or 0.08 in), brownish to blackish crust that is actually the alternate reproductive phase (the tetrasporophyte) of the Turkish Washcloth (Mastocarpus). The crust is firm but not hard: one can sink one’s fingernail into it. Its surface is smooth but sometimes shows faint concentric scalloping. Habitat: This very resilient, perennial phase can be extremely long lived, to 90 years or more; it is common on high to low intertidal rock in protected to semi-exposed habitats. Similar taxa:  Ralfsia